Environmental embrittlement and grain boundary segregation of boron in Ni[sub 3](Si,Ti) and Co[sub 3]Ti alloys
- Tohoku Univ., Sendai (Japan). Inst. for Materials Research
- Nippon Steel Corp., Chiba (Japan). Technical Development Bureau
Recent observation for environmental embrittlement of Ni[sub 3](Si,Ti) and their alloys showed that boron doping has the effect of suppressing the environmental embrittlement. The room temperature tensile elongation of these alloys doped with boron was insensitive to the testing atmosphere and also strain rate, and was then higher than those of alloys without boron, while the room temperature tensile elongation of alloys without boron was lower in air than in vacuum, and also at a slower strain rate than at a higher strain rate. Boron is strongly enriched in grain boundaries in the case of Ni[sub 3]Al alloy. On the other hand, boron doping into Co[sub 3]Ti alloys does not have the effect of suppressing the environmental embrittlement. In this case, it is postulated that boron does not segregate, or little segregates, to grain boundaries in Co[sub 3]Ti alloys. However, direct observation for grain boundary chemistry has not yet been performed on alloys of both Ni[sub 3](Si,Ti) and Co[sub 3]Ti. The tensile results are summarized for undoped and boron-doped Ni[sub 3](Si,Ti) and Co[sub 3]Ti alloys, respectively. Both alloys of undoped Ni[sub 3](Si,Ti) and Co[sub 3]Ti tested in air showed reduced tensile elongation. However, boron-doped Ni[sub 3](Si,Ti) alloy tested in air did not show reduced tensile elongation while boron-doped Co[sub 3]Ti alloy tested in air did. To verify the argument for environmental embrittlement and grain boundary segregation of boron, a comparison of the grain boundary chemistry between two alloys of boron-doped Ni[sub 3](Si,Ti) and Co[sub 3]Ti is necessary. In this work, the results of Atom Probe Field Ion Microscopy (APFIM) and Auger Electron Spectroscopy (AES) are shown for the grain boundary composition of Ni[sub 3](Si,Ti) and Co[sub 3]Ti alloys doped with boron, respectively. Based on these observations, some implication for the correlation between environmental embrittlement and the boron doping effect is discussed.
- OSTI ID:
- 5875591
- Journal Information:
- Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 29:12; ISSN 0956-716X; ISSN SCRMEX
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
BORON ADDITIONS
BORON ALLOYS
COBALT ALLOYS
EMBRITTLEMENT
GRAIN BOUNDARIES
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
SILICON ALLOYS
TENSILE PROPERTIES
TITANIUM ALLOYS